The big dipper's 2 end stars are called the pointer stars because they point toward polaris.

Figure below shows the pointer stars and polaris, which they appear to point towards

Tides

The rising and fallling of ocean water as a result of the Moon's gravity and Earth's gravity.

Figure below shows how the Moon influences the tides, along with the caption below.

Phases of the Moon

The monthly progression of changes in the appearance of the Moon that result from different portions of the Moon's sunlit side being visible from Earth.

The image below shows the phases of the Moon and how they are seen from Earth.

Lunar eclipse

When the full Moon passes through the umbra position of Earth's shadow so the Earth is between the Sun and the Moon.

Figure below (A) shows the Moon passing through Earth's shadow. The red Moon (B) beside it is an example of what the Moon would look like during a Lunar Eclipse.

Solar eclipse

When the shadow of the Moon falls on Earth's surface.

The moon is between the Sun and Earth during a new Moon.

Happens twice a year and can usually only be seen from very specific, often remote places on Earth's surface.

This is NOT safe to look at with the bare eye.

Figure below (B) shows the Shadow of the Moon on Earth's surface. The Black Moon with the Sun behind it (A) is what a Solar eclipse would look like from Earth.

Why do we have seasons?

On Earth, we have seasons because the Earth is on an axis. In Summer in North America, the Northern hemisphere is facing the Sun so it's rays are concentrated on the surface. In winter, the Northern hemisphere is not facing the sun so the light is spread out on the surface. Concentration of Sun's rays results in warmer weather, and when the rays are spread, it results in colder weather.

Figures below show the Sun's rays on Earth in both a concentrated way and a 'spread' way.

Figure below shows how the Earth is on an axis so the Northern hemispher ha summer solstace on June 21st.

Planet

An object that orbits one of more stars in spherical, and does not share its orbit with another object.

i.e.- Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune.

Table below shows which planets are inner (Between the Sun and Mars)and which are outer (After Mars)

Solar system

Made up of the planets, the Sun, and other smallers objects which are kept in the solar system by the Sun's gravity.

Figure below shows the planets, the Sun, and other small objects in the solar system

Retrograde motion

The movement of an object in the sky, usually a planet, from East to West, rather that it's normal West to East

Due to Earth moving faster than outer planets causing it to catch up and move between them

Figure below shows what a planet in retrograde motion appears from Earth

Astronomical unit

The average distance between Earth and the Sun, about 150 million km or .

Orbital radius

Average distance between the Sun and an object orbiting the Sun.

This number is expressed in astronomical units.

Geocentric model

A model of the planets by Ptolemy stating that all planets and the Sun revolved around the Earth in perfect circles.

Figure below is the geocentric model, with geo meaning Earth (the Earth is the center of the solar system)

Heliocentric model

A model of the planets by Copernicus stating that all planets revolved around the Sun in perfect circles.

It was later changed by a J. Kepler stating that the planets orbit are ellipses.

Figure below shows the Heliocentric model with Helio meaning Sun (the Sun is the center of the solar system)

Comet

An object composed of rocky material, ice, and gas; comes from the Kuiper Belt or Oort Cloud.

Often refered to as shooting stars

Asteroid

An object in space that ranges in size from from a tiny speck, like a grain o sand, to 500 km wide; most asteroids originate in the asteroid belt between Mars and Jupiter.

Section circled in white below is the asteroid belt

Meteoroid

A piece of rock moving through space

Meteor

A meteoroid that hits Earth's atmosphere and burns up

Meteorite

A meteoroid that is large enough to pass through Earth's atmosphere and reach the ground, without being totally burned up